According to a major discovery featured in the journal Nature Communications, cardiac patients might soon be able to have pig hearts beating in their chests, in what might prove to be a significant advance in cross-species organ transplantation.

In light of the dire shortage of organ donors, medical science has been long searching for ways it could save human lives with the help of animal hearts, lungs or livers. However, organ rejection has remained a stubborn obstacle in the way of success.

However, a team of scientists from the United States and Germany has reported the successful transplantation of pig hearts in baboons, primate cousins of humans, and keeping them alive for a record 2.5 years.

They used a combination of targeted immune-suppressing drugs and gene modification to achieve this amazing feat.

According to study co-author Muhammad Mohiuddin of the National Heart, Lung and Blood Institute in Maryland, this could be the intermediate step that brings science closer to using these organs in humans.

Mohiuddin said that organ transplants between different species – also known as xenotransplants – could hold the key to saving thousands of lives annually, lives that would otherwise be lost because of the shortage of human organs available for transplantation.

In the latest experiments with five baboons, the group of researchers broke their own records by getting the hearts to survive for up to 945 days.

While the new hearts did not replace those of the monkeys, they were connected to the circulatory system through the baboon abdomen via two large blood vessels.

This method that attempts to lower the risk of organ rejection keeps the baboon’s own heart pumping the blood while the transplanted heart beats like a normal heart. Donor organs are often perceived as a threat by a recipient’s immune system because it is foreign to the body.

For the trials, the donor organs were taken from genetically-modified pigs; in other words, the high tolerance of the pig to the immune response made the hearts invisible to the recipient’s natural defense system.

Also, the baboons were administered drugs that suppress the immune response. But while this achievement is encouraging, are pig hearts safe for humans?

Give our genetic proximity to primates, these animals were long thought to be the best donor candidates. However, experiments going back to the 1960s showed that primate kidneys, hearts, and livers were rejected in a matter of months.

So maybe pigs are better donors, which we’ll find out after Mohiuddin’s team experiments with full pig-to-baboon heart transplants. According to him, pig hearts could eventually make their way into human chests.
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